Elle Fanning is an acclaimed actress who has starred opposite the likes of Matt Damon, Brad Pitt, and Annette Bening. But she's also 14 years old. So she can be forgiven for dissolving into a fit of laughter when asked about her first onscreen kiss.

On Friday, Dec. 21, the Super 8 star stopped by the Tonight Show With Jay Leno to promote her latest flick, Ginger & Rosa, which features the teen's inaugural movie lip-lock. Asked about the smooch by Leno, Dakota's little sister -- in a white Chanel frock -- blushed and giggled.

"It was funny because the boy in that scene, we had never met each other until that day," she said of the kiss. "And it was one of the last days on set, so it was like the director was building up to this scene."

Ever the professional, the actress and her fellow thespian got right down to business. "We were like, 'Hi, how are you?' and then just started kissing," she explained, laughing.